The attitude of Linux users who believe that Microsoft is the work of the devil and that Bill Gates is the anti-Christ who lives in a dark castle above the thunderclouds guarded by evil winged monkeys.

Microsoft is a closed society of evil-doers who don't believe in sharing. They want to crush any attempts to download free music or DVD's and make everyone pay for their crappy operating systems that are riddled with errors and security flaws. Their eventual goal is to close down libraries because that is a form of piracy in their closed mind-set. As opposed to open-source.

Sentiment that has risen in the computer geek community that opposes hard work, perseverance, and good old fashioned capitalist competition.
While open source is a completely valid direction to go with computing, certain agoraphobic uber-geeks (usually 35 y/o morbidly obese virgins who live on cheetos, kid porn, and battlestar gallactica) resent Bill Gates and his company for their colossal success over the past couple decades. Their animosity likely arises from the fact that they have never done anything useful in their entire lives, despite being very skilled on computers, so they turn their ill-will toward someone who they wish they could become.
Similar to anti-apple.